In his first-ever interview, the sole Australian survivor of the Waco siege has revealed to 60 Minutes what really took place during the 51-day stand-off, and why he believes crazed cult leader David Koresh will one day return to Earth as the son of God.

Turnbull weighs up frontbench reshuffle

Attorney-General George Brandis says his future is in the prime minister's hands, as speculation mounts about a pre-Christmas reshuffle.

The Nationals are understood to be pushing for five spots in cabinet after the elevation of Bridget McKenzie - who is not currently a minister - as party deputy leader.

That is despite the party's proportion of the joint coalition party room falling just short of what is needed to get a fifth cabinet post.

Malcolm Turnbull may boost the size of his cabinet from 21 to 22 to accommodate the junior coalition partner, which has had a morale boost in the wake of Nationals leader Barnaby Joyce's by-election win.

Senator Brandis has been the subject of speculation for months that he will take up the role of high commissioner in London, replacing former Liberal minister Alexander Downer.

Asked whether he was ready to step back from his ministerial role, Senator Brandis told ABC radio on Friday: "There's always more work to do in the attorney-general's portfolio, but of course, we are always all in the hands of the prime minister."

"It's been a very, very busy year and ... the last few months have been areas of significant policy reform within this portfolio that I'm very proud of."